


A Collection of Sanster

by BlueDysania



Series: Collections of [2]
Category: Undertale (Video Game)
Genre: Dissociation, Dom W. D. Gaster, Emotional Hurt/Comfort, Implied Attempt of Murder, M/M, Other Additional Tags to Be Added, Reincarnation, Reunions, Science, Small Sans, Soulmates, Stars, Sub Sans, W. D. Gaster is a Boss Monster
Language: English
Status: In-Progress
Published: 2018-06-29
Updated: 2018-08-12
Packaged: 2019-05-30 05:35:53
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,458
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15090116
Author URL: https://archiveofourown.org/users/BlueDysania/pseuds/BlueDysania
Summary: scenes of varying length and genre featuring Gaster and Sans!tags will be added with each chapter, warnings in the Notes if needed, as well as a NSFW in the title of any chapter that requires it.





	1. I Want to Sink in You

**Author's Note:**

> Requests OPEN. See bottom Notes.

**Summary for the Chapter:**

> Monsters on the Surface and everything is going pretty well for monsterkind. For Sans however... things could be better. 
> 
> He's found Gaster... right? 
> 
> Gaster assures him that he won't disappear again.

Gaster finds the Surface utterly fascinating. Having been one of the few monsters who remembered what it had been centuries ago, he could hardly contain his curiosity at seeing such profound changes of the world during monsterkind's absence. He spent countless hours, days, weeks, studying the humans and their impact on the world and had countless devices brought from the Underground Laboratories as well as human inventions to assist him.

Yet the largest device in his newly constructed lab was the _telescope_.

A grand, expensive, shiny gift for the monster who deserved so much more.

Sans had been inseparable from the device the moment Gaster told him it was his. He'd spent every night from dusk to dawn charting the skies.

Gaster had diligently worked around the telescope's platform but had often stopped and looked upwards at Sans' diminutive form encased in steel and glass and nearly iridescent in his joy.

After being released from the Void, Gaster had needed extensive time for recovery and Sans had been nearly glued to his side. When he wasn't crying in relief he would be breaking down from all the dark emotions he'd been keeping bottled up. It was a good thing, Gaster knew, that Sans was happy to stay by his side. After certain events came to light, and to _memory_ , Gaster had seen the horror on the Majesties faces, on dear Alphys' and General Grillby. The idea of bearing such weight that had been on Sans' shoulders had been enough to sentence him to a type of therapy of his own.

Gaster knew only that Sans wrote in a journal whenever he could bear it to relive what he had witnessed. It had been years now and neither of them were as they once were. Too much had happened, too much experienced to return to the former state of things.

Yet in the silence of the lab, only accessible to them in the night, sometimes it felt like old times.

 

Other times… Gaster felt past sink its teeth into his Soul.

 

Tonight, was one of those times.

Sometimes Sans looks at him as though he isn’t there.

He turns, about to ask if Sans would like to wrap up and return home for the night, and feels a bolt of panic shoot down his back when he sees Sans frozen where he'd dismounted the telescope, shrunken pinpricks of light staring from across the lab at him. Who knows how long the skeleton had been standing there as though made of stone.

He _does_ know that Sans has retreated somewhere, triggered by some sinister thought.

It could take hours to snap him out of this state. The first time, it _had_ taken hours.

No one had known what to do, only that Sans wouldn't - _couldn't_ \- respond to them. Gaster could only conclude that he'd slipped into a state of shock somehow. He had noticed, however, that no matter who moved in front of Sans, his eyelights had been trained on _him_.

An epiphany came to him. Realizing what may have caused this episode, Gaster had curled himself around the small skeleton, shrouding him in his cloak, enveloping him completely in his presence. He’d murmured nonstop uncaring about the audience surrounding them. He'd uttered both reassurances and inane scientific babble that they shared together in private moments.

Nearly three hours later, Sans' hand had gripped his back tightly and the little skeleton had pulled away with a sleepy blink asking, "feeling cuddly today, doc?"

It had been a scare for everyone except Sans who didn't seem to realize the state he had been in.

The second time it occurred, Gaster had permission given beforehand to test Sans' magic and physical state. Data recorded, he had then promptly proceeded to wrap his arms around the smaller and coax him back to reality.

It wasn't a lethal state but it clearly indicated a type of deep-rooted detachment and dissociation. This retreat was the only way Sans felt like he could protect himself from the crippling doubts and fears in his brilliant mind.

If left unattended, it could be potentially damaging.

Luckily the cause was always the cure and though it hurt Gaster to see Sans suffering he would never be able to refuse the attention he needed.

But that was then and this was now.

Gaster quickly crossed the distance between them, kneeling on the ground. He smoothed a hand across Sans’ cheek tenderly, but firmly. The worst thing he could do right now was ignore his little lover. So, he knelt and enclosed him in his arms, willing the unresponsive monster to react.

“ _I am here, Sans._ ” He soothed softly in his real voice, “ _I am in front of you. I am holding you in my arms._ ”

His WingDings font-speak had a habit of soothing Sans back to awareness faster than anything else despite the fact Sans likely could not understand the sound of it. He picked up the skeleton and cradled him close to his chest, continuing to whisper a litany of soft comforts as he climbed the ladder that led to the observation deck on the roof of the lab.

He settled in one of the chairs, still carrying his precious burden, and pulled the endless folds of his cloak around them. The stars twinkled down from their astronomical expanse as he spoke of everything and nothing and always repeating,

 

" _I will never leave you again._ "


	2. Under the Bed

**Summary for the Chapter:**

> Sans is scared of the thing under his bed. He doesn't know that the 'monster under his bed' is the only thing that keeps him alive.
> 
> And it has been waiting for him.

**Notes for the Chapter:**

> Making this very clear! Gaster is not creeping on Sans as a child, he has no sexual feelings in the least right now. There are very clear restrictions that you will see as you read. PLEASE be aware that nothing underage is intended! It shouldn't read like that in any way, but I wanted to clarify just in case.

Sans is a normal child in many ways and a peculiar child in others.

Most parents lament the way their children do not follow the basic hygienic routines or help out with chores. Sans is odd in the way that he does all that and more.

The little skeleton, barely a few years older than a babybones will help clean the dishes, put away the dishes he can reach, and then ask if his parents need anything else done. He will retreat to the bathroom after making sure three times that, no there is nothing else he needs to do. There he will take a bath all by himself and then help to bathe his little brother who is a babybones.

He reads a Fluffy Bunny book while his mother rocks Papyrus in her arms and settles him to sleep. Sans gives him a kiss goodnight and scans under the crib while his mother isn't looking. Satisfied that his brother is asleep and safe he goes to his room.

On his bedside table there is a tiny cup with three pills of different sizes inside it. He takes each one and looks at his bed.

Before stepping back and beginning to clean his room. He takes his time as he moves about the room, rearranging the few toys he has, adjusting his thin drapes, and pulling on his nightshirt. When Sans can do nothing else, he tentatively approaches his bed.

He doesn't look under the bed.

Once he is close enough, he all but leaps into the bed and hurriedly throws the covers over his head.

Sans hopes it will be a quiet night and waits with closed sockets to either fall asleep or hear something moving about in his room that should not be. He doesn't want to hear the floor creaking or strange static that sounds like words garbled through a blender.

He doesn't want to peek under the bed or in the far corners of his bedroom and see a white face with two large gaping eyes with lines coming down from one and up on the other. Doesn't want to see hands floating in the darkness, parts of a white body disappearing and reappearing as it moved. Glimpses of the creature that haunts him in the dark.

He's so _scared_ of the thing under his bed and he can't do anything about it.

He wishes he could go to his parents and ask them to wait with him until he falls asleep… but they no longer entertain his fear.

And he doesn't want to be a bother.

Sans forgets to be afraid as he curls into a small ball under the sheets. He isn't blind, he can see his parents are tired and frustrated and he knows it's his fault. The medicine he has to take every night is to keep him healthy. He was born with a Soul much to weak. He doesn't know why but it requires expensive doctors and medicine and his parents have long stopped reassuring him with loving smiles that everything is 'okay'.

He huddles under the blanket, fighting tears, and doesn't realize the cold chill coming over him is not from fear before losing consciousness.

 

* * *

 

The creature that unfolds itself from beneath the bed is tall and looms over the shivering ball under the bedding that is years too old to be adequate, thin and tattered at the edges. Slender fingers gently grasp the sheets and pull them back, revealing the tiny child beneath.

There is no need to hide or conceal himself now. A dark frown graces the marble-smooth face and black eyes flare with violet light as he reaches out and summons the child's soul.

The bed is bathed in a weak cyan glow and it only makes his frown turn darker. There was once a time this soul shone like a miniature supernova in his hands, turning the room a beautiful blue under its radiance. He studies the weak glimmer and pulses the soul gives out and senses the negativity that envelops the child's thoughts.

He brings it closer to his own and allows a single pulse of warmth to echo outward; all that he can give for now.

The haunted look clears from the child's face and he is satisfied but not done yet. The gray of his skull and shortness of breath is something that is familiar to him now and his being shudders in fury that such a thing is no longer a surprise.

A conjured hand picks up the tiny cup the child's parents had placed onto his nightstand. He crushes it and lets it fall to the ground, blackness seething from the cloak draped over his body and painting the room in darkness.

He apologizes to Sans for any discomfort as he begins to run his fingers across the surface of the tiny soul, feeling for the traces of the poison that had been fed to him and pulling it out as swiftly but efficiently as possible. He would need to pay Sans' parents another visit tonight. Evidently his last impression had faded enough for them to try and kill his soulmate again.

He had waited centuries for his precious one to return. Through the last peaceful days on the Surface, to the Great War with the humans, and even the retreat into Mount Ebott he had walked the world alone and longing eagerly for the other half of his being.

To find him in the Underground had been a source of great relief. To find him suffering from such low HP and a soul that struggled to contain the magical potential within it, a mixture of sadness and interest. He could not approach Sans now, not until he was old enough, but there was no rule that said he could not watch over his soulmate; and how glad that he did.

He'd approached the King and offered his knowledge in return for a position as Royal Scientist. Let the fool king believe that he sympathized with their imprisonment, he cared only that as Royal Scientist he was in a perfect place to properly take care of his soulmate.

The first night that he arrived to the small home on the edge of Hotland, he had promised himself, and Sans, that he would not interfere. Sans would grow and learn and live undisturbed until he came of age and finally Gaster could go to him in the light.

He'd panicked to find Sans, just a babybones in a pristine crib, cool to the touch and soul nearly dark. It had taken the entire night to coax the little soul back to shimmering brightness and remove the traces of toxins that had dimmed it.

The violet eyelights turned sharp at the memory and only the small contented sound from Sans as his breathing returned to normal softened his demeanor once more. He gently lowered the now glimmering soul back to its owner and watched it sink back into Sans, causing the room to return to its natural state.

Gaster ached to bring his soulmate away, to safety. Yet even if doing so would spare him from the pain and neglect, he could not interfere. It was not allowed. Sans would understand when the time came to reveal all the secrets. If they wanted to continue this cycle, if Sans chose to come back to him after their time was over once again, then this was the way it had to be.

At least Sans had Papyrus.

That little soul had come from nowhere. Usually, anyone monster that gave life to his dear Sans would be unable to have another child. Yet…

Gaster could recall looking down into Papyrus' crib, curious yet distant, and be startled from the vibrant orange eyelight that flared to life and looked directly at him. Then, upon seeing him, a monster that could make Boss monsters tremble and shy away, Papyrus reached up with a giggling smile. The soul that sung of bravery was open and accepting, a mark of who the babybones would one day be.

He had kept an eye on that child as well. When the time came for Sans to return to him, he had made arrangements to take in his soulmate's brother as well. There was no mistaking the utter love that Sans had for Papyrus, the way he cared for him. And though a part of him was jealous of having to share his soulmate's love, the rest of him was content to see Sans smile.

Perhaps a small part of him found Papyrus worthy of his attention as well.

Gaster tucked Sans in and then cut away a piece of his cloak to settle over his soulmate. The shivering that came from the natural chill in the air ceased. It would fade in a few hours but for now it was all he could do.

Well… not all. If subtle impressions in nightmares no longer sufficed… perhaps he should introduce himself to his soulmate's parents early.

A ghastly smile split across his face as he glided toward the door at the end of the hall. He slipped into it silently and the Void swallowed the room. He would not be kind and it would not due to wake his precious Sans with the sound of screaming.

**Author's Note:**

> Questions, Comments, and Requests at [BlueDysania](http://bluedysania.tumblr.com/).


End file.
